Ceramides + Cholesterol + Fatty Acids

Why it is here

The barrier's own vocabulary, restocked. The stratum corneum is built from three lipid families, and putting only one or two of them back turns out to be worse than none. The ratio is the point.

The stratum corneum lipid matrix is roughly half ceramides, a quarter cholesterol and a quarter free fatty acids, arranged in lamellar sheets. Deliver one or two of those and the sheets cannot assemble; the 1996 work found that single and paired lipids actually delayed recovery after damage. Deliver all three in an equimolar ratio and recovery is normal. Skew the ratio up to threefold toward one lipid and recovery accelerates. In older skin, the lipid to skew toward is cholesterol.

The receipts

1. Only equimolar mixtures of ceramides, cholesterol and free fatty acids allow normal barrier recovery, and further acceleration occurs as the ratio of any one of the three is increased up to threefold; similar preliminary results were obtained in damaged human skin.

   Optimization of physiological lipid mixtures for barrier repair. Journal of Investigative Dermatology, 1996. in vivo animal, n = murine skin, with preliminary validation in damaged human skin. PMID 8618046

2. The cholesterol-dominant optimal molar ratio mixture significantly accelerated barrier recovery in chronologically aged human skin at 6 hours, while the free fatty acid dominant version significantly delayed recovery in aged mice.

   Optimal ratios of topical stratum corneum lipids improve barrier recovery in chronologically aged skin. Journal of the American Academy of Dermatology, 1997. in vivo animal and human, n = aged hairless mice and aged human skin at 80 plus or minus 5 years, n equals 6 for the human arm. PMID 9308554

3. A ceramide-dominant physiologic lipid emollient substituted for the previous moisturizer improved SCORAD in 22 of 24 patients by 3 weeks, with parallel improvement in transepidermal water loss, stratum corneum integrity and hydration.

   Ceramide-dominant barrier repair lipids alleviate childhood atopic dermatitis: changes in barrier function provide a sensitive indicator of disease activity. Journal of the American Academy of Dermatology, 2002. cohort, n = 24 children with stubborn to recalcitrant atopic dermatitis. PMID 12140465

In practice

Typical use

Roughly 2 to 5 percent total physiologic lipid, in a molar ratio around 3:1:1. Which lipid takes the 3 is the interesting decision, and the published answer depends on the skin: ceramide-dominant in atopic dermatitis, cholesterol-dominant in aged skin.

Pairs with

Glycerin, Squalane, Wax Esters, Niacinamide

Keep apart from

Layering a single-lipid product on top immediately after damage: the whole point of this system is that the proportion is the active. Adding a large excess of one lipid on top is exactly the manipulation that delayed recovery in the source papers.

Cautions

None notable. This is the skin's own material in the skin's own proportion. Slow rather than dramatic: the human barrier readouts in these studies move over hours for recovery rate and over weeks for clinical appearance.

Questions people ask